1. Field of the Invention
The invention relates to a control system that controls a running characteristic, such as a driving force characteristic, a shift characteristic, a steering characteristic and a suspension characteristic, on the basis of the acceleration of a vehicle.
2. Description of Related Art
Driver's expectations and requests to a vehicle are various for each driver. Some drivers prefer running of a quick change in behavior (so-called sporty running), and others prefer smooth relaxed running (so-called mild running) on the contrary, so driver's tastes are various. In contrast to this, the running characteristic of a vehicle is predetermined in a design phase on the basis of the type of a vehicle, or the like, and may not always agree to a driver's driving orientation (or a driver's driving taste).
In an existing art, there have been various attempts to improve such disagreement between the running characteristic of a vehicle and the driving orientation of a driver as much as possible. For example, Japanese Patent Application Publication No. 06-249007 (JP-A-06-249007) describes a driving force control system that uses a neurocomputer. The driving force control system is configured to learn the correlation of an acceleration against an accelerator stroke and a vehicle speed as a required acceleration model and then compute a throttle opening degree on the basis of a deviation between the required acceleration model and a second reference acceleration model that incorporates a driving orientation and a deviation between the second reference acceleration model and a standard first reference acceleration model.
In addition, Japanese Patent Application Publication No. 2007-290650 (JP-A-2007-290650) describes a system that uses applied acceleration information to control the steering, acceleration or deceleration of a vehicle. The system is configured to start accelerating the vehicle when an applied lateral acceleration (that is, lateral jerk) is close to zero. Furthermore, Japanese Patent Application Publication No. 2005-186674 (JP-A-2005-186674) describes a system that is configured to estimate a driver's driving orientation on the basis of a jerk. Yet furthermore, Japanese Patent Application Publication No. 2009-508751 (JP-A-2009-508751) describes a system that controls suspensions on the basis of a longitudinal jerk and a lateral jerk. The system is configured to change the characteristic of each suspension on the basis of a longitudinal jerk and a lateral jerk. Then, Japanese Patent Application Publication No. 2009-530166 (JP-A-2009-530166) describes a system that is configured to evaluate a driver's driving style on the basis of the rate of variation in acceleration (that is, jerk) and then to set the operating state of a sub-system of a vehicle on the basis of the evaluated results.
JP-A-06-249007 describes that a driver's driving orientation, a driver's driving intention, or the like, is detected or estimated on the basis of the running condition of a vehicle and then the detected or estimated results are incorporated into control over the vehicle. In addition, there is known that a jerk, that is, the time differential value of an acceleration, is used in order to detect or estimate a driver's driving orientation, a driver's driving intention, or the like, as described in JP-A-2007-290650, JP-A-2005-186674, JP-A-2009-508751, JP-A-2009-530166, and the like. However, there is still room for improvement in better adapting the running characteristic to a driver's driving orientation or driver's driving intention or achieving higher drivability.